A modern irradiator is an essential research tool for biology and medicine. Twelve major users are identified in this proposal that is requesting a high activity irradiator with a Cs-137 source. The instrument is made by the JL Shepherd Company, Model JL81, and included in the request are accessories required by state and federal regulatory laws. Investigators at the University of Colorado at Denver and Health Sciences Center (UCDHSC) currently use a Co-60 source that has been in place at the 9th and Colorado Blvd. campus in Denver since 1978 and is due for replacement of the radioactive source. Over 90% of the investigators that use the radiation source have moved to our new Fitzsimons campus in Aurora. The remaining faculty at the 9th Ave. campus will move to Fitzsimons by 2007, at which time the Co-60 source will be decommissioned because the cost of a new source and moving is more expensive that buying a new irradiator. A new irradiator at the Fitzsimons site will be essential for continuing the NIH-funded research of these investigators. The institution has identified space for such an instrument in Research Complex I at the Fitzsimons site. The JL81 irradiator with a Cs-137 source was selected because it has the flexibility of a wide range of in vitro and in vivo applications ranging from the irradiation of cells in culture to that of animals, from mice to sheep, and attenuation for deep dose or superficial irradiation applications. The irradiation facility will be managed as a new core facility in the University of Colorado Cancer Center (UCCC). The UCCC has 17 years of experience as a matrix cancer center and has a mature and functional structure that encourages productivity, promotes interactions and collaboration, and positions the UCCC to maximize the resources at the UCDHSC, its affiliates, and the community. The 15 major users will pursue questions integral to their NIH-funded research and the availability of this instrumentation will significantly enhance, and in many cases is crucial for, their NIH-funded research. In addition, it is expected that obtaining the JL81 irradiator and housing it at the new Fitzsimmons campus will facilitate development of new collaborations among cancer center members that will result in additional users with NIH level funding. Relevance: Obtaining funds to purchase a new JL 81 irradiator for the UCDHSC Fitzsimons campus will provide an important conduit for building upon a foundation of research related to cancer diagnosis and therapy. Many Cancer Center members with NIH funding are committed to the eradication of cancer and realize that preclinical investigations are crucial for translating findings into human clinical trials. The JL 81 irradiator is an important component of this foundation of cancer research and will facilitate the preclinical experiments necessary for translation at the new UCDHSC Fitzsimons campus. [unreadable] [unreadable] [unreadable]